Tycho Brahe (1546-1601) occupies an exalted position in the pantheon of science as the founder of modern
observational methods in astronomy. Astrologers as well as astronomers have good reason to be grateful to him. It was Tycho and his protégé Johannes Kepler who prepared the way for the pinpoint accuracy of the ephemerides and calculation programs that we take for granted today. And, to quote Arthur Koestler, Tycho really was 'a refreshing exception amongst the sombre, tortured, neurotic geniuses of science'. [1] He was an imperious, hard-drinking aristocrat whose devotion to precise observation was motivated by his devotion to astrology. He was also an alchemist and lived for twenty years on a fantastic 'sorcerer's island' near Hamlet's castle of Elsinore, ending his days as Imperial Mathematicus at the court of the Holy Roman Emperor. In the history of astrology and astronomy, Tycho stands out as one of the most bizarre and colourful of all Urania's children.

Educating Tycho

Tycho was born into a noble Danish family at their ancestral seat of Knudstrup on 24th December 1546. [2] His father, Otto Brahe, was a privy councillor to the King of Denmark; his uncle, Jörgen Brahe, was an admiral in the Danish navy. Before Tycho's birth, his father had made a strange pact with Jörgen. Being childless, Jörgen had somehow persuaded Otto to promise that if he had a son, the child would be handed over to Jörgen and brought up as his own. Obligingly, Otto's wife, Beate, gave birth to twin sons, but one of them was still-born and Otto went back on his promise. Jörgen waited until another child was born to Otto and Beate a year or so later, then coolly abducted their firstborn, Tycho. After making some murderous threats against Jörgen, Otto finally accepted the fait accompli, knowing that Tycho would be brought up as a nobleman and would eventually inherit Jörgen's fortune.

At his uncle's estate at Tostrup, Tycho received an education appropriate to his social station and in 1559 he went to Copenhagen University to study philosophy and rhetoric in preparation for a career as a statesman. In 1560, however, the heavens directly intervened in Tycho's life and altered its course irrevocably.

The solar eclipse of 31st August 1560 at 7° Virgo 51' was total in the extreme west of Europe. At Copenhagen it was partial but still attracted Tycho's attention. Astrology was an everyday topic of conversation amongst his fellow students and Tycho's interest was aroused. When he saw the eclipse take place at the predicted time, it struck him as miraculous that the motions of the planets could be forecast so accurately. He immediately acquired an ephemeris and the complete works of Ptolemy and set about learning how it was done.

Jörgen Brahe disapproved of Tycho's new passion. He regarded stargazing as a vulgar pursuit far beneath the dignity of a Danish nobleman. Determined that Tycho should continue the family tradition of service to the state, Jörgen packed him off to study law at Leipzig University under the supervision of a tutor, Anders Vedel, who had strict instructions to ensure that Tycho attended to his proper studies. But by then it was too late. Showing little interest in law or statecraft, Tycho continued to study astronomy in secret, making observations when Vedel was asleep and somehow contriving to spend most of his allowance on books and instruments. Vedel eventually gave way to Tycho's persistence and turned a blind eye to his extra-curricular activities, after which they became good friends.

Tycho's awe at astronomers' predictions of celestial events turned to disillusion as his own observational skills developed. The standard Alphonsine Tables, based upon Ptolemy's theory of planetary motion, had been computed in the mid-13th century by Arabic and Jewish astronomers working for King Alphonso the Wise of Castile. With the invention of the printing press they became the first set of planetary tables widely available in Europe. More recently they had been superseded by the Prutentic Tables (1551) compiled by Erasmus Rheinhold and the Ephemerides Novae (1556) of Johannes Stadius, both of which were based upon the new heliocentric theory of Copernicus. In 1563, at the age of 17, Tycho observed a conjunction of Jupiter and Saturn using a simple pair of compasses held close to his eye to measure the angle between the two planets on successive nights as the conjunction approached. On the morning of the 4th September they were so close together that no angle was discernible between them. Tycho was dismayed to find that the old Alphonsine Tables were a whole month in error regarding the timing of the conjunction and even the Prutentic Tables were wrong by several days. This was the beginning of his lifelong devotion to precise observation.

Tycho continued his education until the age of 26, attending the universities of Wittenburg, Rostock, Basle and Augsburg and making the acquaintance of many prominent mathematicians, astronomers and astrologers on his travels. At Rostock he attended lectures given by Levinus Battus, a professor of medicine and a disciple of Paracelsus, who inspired Tycho's own interest in medicine and alchemy. Also at Rostock, in December 1566, he quarrelled with a fellow student, another hot-blooded Danish nobleman, over which of them was the better mathematician. They settled the dispute with a sword fight during which Tycho suffered the indignity of losing his nose. He replaced it with a false nose made from an amalgam of silver and gold.

Ostracised by most of his family because of his peculiar interests, Tycho went to live with his maternal' uncle, Steen Bille, who was devoted to alchemy and depended upon favourable planetary configurations to conduct his experiments, in which Tycho assisted him. Tycho also made use of the facilities of his uncle's workshop and laboratory to build his own observing instruments.

Tycho's Star

In November 1572, a new light appeared in the sky and caused consternation amongst the astronomers of Europe. It flared up, brighter than Venus, amongst the stars of Cassiopeia and remained visible for nearly eighteen months. When it first appeared, the new light was bright enough to be clearly visible in daylight. Its brilliance gradually faded and by April 1574 it had disappeared from sight. Today we would recognise it as a supernova, but to 16th century astronomers it was something entirely alien. Apart from the biblical Star of Bethlehem and a tradition that the Greek astronomer Hipparchus had observed something similar during the 2nd century BC, such an occurrence
was unprecedented in European astronomy. [3] It was vital to determine whether the new light changed its position relative to the background of fixed stars. If it moved, it could be classed as a sub-lunar phenomenon, a kind of atmospheric disturbance, as comets and meteors were believed to be. If it didn't move, however, it meant that a new star had appeared in the sky - in contradiction of the doctrine taught by Aristotelian professors and the Church, that the heavens were eternal and that all change, all 'generation and decay', was confined to the Earth and its surrounding atmosphere.

Tycho first saw the new light on the evening of 11th November 1572. He had just invented a new instrument: a prototype sextant with arms nearly six feet in length and a scale graduated to single minutes of arc. Tycho used it to measure the angle between the new object and various fixed stars, and he repeatedly measured the same angles over the whole period of the object's visibility. The sophistication of Tycho's method becomes clear when compared to observations recorded by other astronomers of the time. The famous Michael Maestlin of Tubingen, for example, simply held a piece of string at arm's length so that it passed between the new light and two nearby fixed stars. He tried again a few hours later and, finding them still in the same straight line, concluded that the new light stood still in the sky. Other observers using equally crude methods disagreed. It was Tycho's meticulous observations which proved beyond doubt that the new star did not move.

In 1575, Tycho published De Nova Stella ('On the New Star'), which gave an exact description of his observations and of the new instrument on which he had made them. His account was later expanded and incorporated into his major work, Astronomiae Instauratae Progymnasmata ('Preparatory Exercises in Restored Astronomy'), published posthumously. He reported that the nova had changed colour during its period of visibility. At first it shone bright and clear like Venus and Jupiter, then it glowed red like Mars, finally fading to a dull gleam, like the light of Saturn. Its celestial longitude placed it in the first degree of Aries. [4] This was at a time when the cycle of great conjunctions of Jupiter and Saturn was about to move into the fiery triplicity. Tycho saw a link between the nova and the approaching 'great mutation' into fire. From a combination of astrology and biblical prophecy, he predicted the decline of the Catholic religion and identified the years 1592-1632 as the period of the nova's greatest influence. It transpired that this coincided almost exactly with the lifespan of Gustavus Adolphus (1594-1632), the great champion of Protestantism during the religious wars of the early 17th century. Tycho's observations and predictions on the nova of 1572 instantly established his reputation as Europe's leading astronomer.

Castle of the Heavens

Basking in his new fame, Tycho set off on a triumphal tour of Europe. Amongst other dignitaries, he visited the Landgrave Wilhelm IV of Cassel, a keen astronomer himself, who urged King Frederick II of Denmark to provide Tycho with the funds to set up an observatory of his own. Eager to encourage the brilliant young astronomer, King Frederick offered him exclusive rights to the beautiful island of Hveen, situated in the strait between Copenhagen and Elsinore Castle where, at the Crown's expense, Tycho could build his house and observatory. He would also receive rents from the island's inhabitants and an annual grant that would make him one of the richest men in Denmark. Naturally, Tycho accepted the offer and proceeded to build his fantastic palace-observatory, Uraniburg - the 'castle of the heavens'.

The foundation stone of porphyry, bearing a Latin inscription stating that the house was to be devoted to philosophy and the contemplation of the stars, was laid with due ceremony on 18th August 1576 'when the Sun was rising together with Jupiter near Regulus, while the Moon in Aquarius was setting'. [5] Surrounded by elaborate formal gardens, artificial fishponds and Tycho's own game preserve, the main building was surmounted by an onion-shaped dome and flanked by cylindrical towers with removable tops where he housed his instruments. The interior was luxuriously furnished and decorated with paintings and murals, one of which depicted Tycho himself presiding over the seven greatest astronomers of history. Clocks, sundials, globes and statues littered the galleries. Tycho delighted in gadgets and novelties and was especially proud of the automata, or moving statues, with which he gleefully startled the distinguished visitors he received from all over Europe - and which earned him a reputation as a sorcerer amongst the islanders of Hveen. Elsewhere in the complex, he installed a printing press, a library, his own pharmacy and an alchemical furnace.

Amongst Tycho's entourage of servants, scholars and assistants was the peasant woman, Christine, who lived with him for 26 years and bore him eight children. They could not formally marry because of Christine's humble origins, but at Tycho's insistence she was treated with the deference and courtesy due to the mistress of Uraniburg. A maid, Liuva Lauridsdattar, later lived with Tycho's sister, Sophia, at Copenhagen, where she practised astrology and medicine and died in 1693 aged 124. Strangest of all Tycho's retinue was his fool, a dwarf called Jepp, who sat at Tycho's feet when he dined, chattering incessantly and receiving occasional morsels of food from his master's hand. Jepp was gifted with second sight. Whenever anyone fell ill at Uraniburg, the dwarf pronounced upon their chances of recovery or death, and he was always right.

Despite presiding over an endless round of banquets and entertainments for visiting dignitaries, Tycho worked relentlessly at his observations. His instruments, built to his own designs and financed by the generosity of King Frederick, were the best ever seen. Two of the most famous were a wall-mounted quadrant with a brass arc seven feet in radius and a celestial globe five feet in diameter upon which hundreds of fixed stars were engraved as their exact positions were determined. In 1584 Tycho built a second observatory, the Stjerneburg ('star-castle'), which was constructed underground so that slight movements and vibrations in the building itself would not affect the accuracy of his observations. Only the domed roofs of the star-castle could be seen above ground level. During his 20 years at Uraniburg, Tycho took pre-telescopic observation to unprecedented peaks of accuracy. The data on planetary orbits which he assembled was especially important, both for its precision and for its continuity.

Tycho also found time to provide an annual astrological almanac for King Frederick and to write detailed reports on the horoscopes of the king's children. The royal horoscopes were presented as handsome bound volumes with up to 300 pages of natal delineations and directions. Tycho's charts were not the square figures generally used by his contemporaries, but circular. He may have been the first astrologer to make regular use of a circular chart form.

The Tychonic System

The Sun-centred theory of the solar system proposed by Nicholas Copernicus had been in circulation for over 30 years by the time Tycho built Uraniburg, but few astronomers accepted it as anything more than a useful calculation device. Tycho didn't like it because it seemed to contradict the Bible. As an impartial observer he investigated the theory but rejected it because he could find no evidence of stellar parallax - just as Hipparchus had done when he investigated the heliocentric theory proposed by the Pythagorean astronomer Aristarchus during the 2nd century BC.

Parallax is the apparent shift in an object's position against the far background when it is viewed from different foreground locations. As a simple demonstration, hold up your thumb at arm's length and see it 'move' when you look at it first with one eye covered, then the other. Tycho reasoned that if the Earth were in motion around the Sun then the nearer stars should show parallax against the more distant stars as the Earth moved through different points on its orbit. His reasoning was correct, but even Tycho's marvellous instruments were not accurate enough to register stellar parallax given the vast distances involved. He remained convinced that the Earth was stationary at the centre of the Universe and developed his own variation on another ancient Greek cosmological system, that of Herakleides, in which the planets orbit the Sun but the whole system was itself in orbit around the central, immobile Earth. [6] The 'Tychonic System' became important as a compromise solution when heliocentric astronomy came into open conflict with Church doctrine during the 17th century.

Despite his conservatism regarding the Earth's orbit, Tycho dealt two major blows to the cosmology of Aristotle and Ptolemy. He had already demonstrated that change could occur in the heavens by proving that the nova of 1572 was a celestial phenomenon. In November 1577, a comet blazed amongst the stars above the head of Sagittarius. According to Aristotle, comets were pockets of burning gas produced in the Earth's atmosphere; they were classified as weather phenomena. Tycho measured the comet's parallax and came to the astonishing conclusion that its distance from Earth was at least six times that of the Moon. Despite their ephemeral nature, comets too were celestial phenomena. Once again Tycho had shown that Aristotle's 'immutable' heavens were subject to change after all.

Tycho and Kepler

In 1596, Johannes Kepler, a 25 year old schoolmaster in a provincial town in Austria, sent Tycho a copy of his first published work, Mysterium Cosmographicum ('The Cosmic Mystery'), in which he attempted to integrate Pythagorean sacred geometry with the Copernican theory of the
solar system. Impressed with Kepler's mathematical brilliance, Tycho invited him to Uraniburg, hoping to convert him to the Tychonic System. On a provincial schoolmaster's salary Kepler could hardly afford to travel to Denmark to meet Tycho, but circumstances conspired to bring them together.

Tycho's royal benefactor, King Frederick II, had died in 1588. He was succeeded by his son, Christian IV. Although Tycho played no part in court politics, the old king's favour and generosity towards him had aroused the jealousy of one or two powerful courtiers who were eager to cause trouble for him under the new regime. Tycho's domineering nature and his sense of self-importance played right into his enemies' hands. His appalling treatment of the islanders of Hveen had become a national scandal. He demanded their unpaid labour on improving his estates and summarily imprisoned anyone who tried to protest. When King Christian admonished him for his behaviour, Tycho's arrogance and lack of tact soon alienated the new monarch. Gradually, year by year, his income and privileges were reduced and in 1597 he decided that the time had come to close down Uraniburg and leave Demnark for good. For two years Tycho wandered across Europe accompanied by a great entourage of family, servants and assistants, and several wagons loaded with his books, furniture, observing instruments and even his printing press. In 1599 the Tychonic caravan arrived at Prague in Bohemia where Tycho was appointed Imperial Mathematicus to the Holy Roman Emperor, Rudolph II, who commissioned him to compile a definitive new set of planetary tables to be known as the Rudolphine Tables. Tycho was given a generous salary and the use of Benatek Castle on the River Iser, which he planned to turn into a second Uraniburg.

Meanwhile the Protestant Kepler was forced to leave Catholic Austria because of increasing religious strife. By chance, in 1599, he met one of Emperor Rudolph's councillors who offered to take him to Prague, where Tycho had taken up residence. Seizing the opportunity, Kepler left Austria on 1st January 1600 and found employment as one of Tycho's assistants at Benatek Castle.

Tycho was the best observational astronomer in Europe, but he lacked the ability to organise his data coherently. Kepler was a brilliant mathematician, yet by Tycho's standards his knowledge of practical astronomy was rudimentary. What could have been a mutually beneficial working relationship was marred by the clash of their personalities. The autocratic Tycho found that he had met his match in the intense, highly-strung mathematical genius. Kepler was eager to gain access to Tycho's records of his 25 years of observation in order to perfect his planetary theory, but Tycho guarded his data jealously. He wanted to make use of Kepler's mathematical abilities in support of the Tychonic System, which he regarded as the crowning achievement of his life's work - but it was
clear that Kepler had ideas of his own. Tycho set Kepler to work on the ongoing observation of the
orbit of Mars. He also made him waste time writing a refutation of the views of a
rival astronomer, which Kepler considered a tiresome and demeaning chore.

Their brief, stormy collaboration came to an end in October 1601 with Tycho's sudden death. Kepler himself recorded what happened in the observatory logbook:

On October 13th, Tycho Brahe... had dinner at the illustrious Rosenburg 's table, and held back his water beyond the demands of courtesy. When he drank more, he felt the tension in his bladder increase, but he put politeness before his health. When he got home he was scarcely able to urinate. [7]

Infection and fever set in, and Tycho died eleven days later on 24th October.

Within a few years of Tycho's death, the telescope had revolutionised observational astronomy. Kepler, who succeeded him as Imperial Mathematicus, finally gained full access to his records. They became a key factor in the formulation of Kepler's laws of planetary motion, which did away with the circles and epicycles of both the Ptolemaic and Copernican theories and gave the first glimpse of the solar system as it is perceived by astronomers today. The collapse of the old cosmology brought astrology down with it - at least so far as science and academia were concerned. Tycho Brahe is one of the last representatives of an age when astrology and astronomy were one, offering an integrated vision of humanity's place in the Universe. Despite Kepler's earnest attempts to clarify that vision in line with the new astronomy, it has yet to be recovered.

J.L.E. Dreyer, Tycho Brahe; (1890) Ascella reprint.
On p.12 Dreyer states: 'he was born between nine and ten o'clock in the morning'. In this article all exact dates have been converted to the New-Style Gregorian calendar which was 10 days ahead of the Old-Style calendar during the 16th century.
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3 ]

Several appearances by 'guest stars' were recorded by Chinese astronomers prior to 1572, but European commentators classified them as comets in order to preserve the Aristotelian doctrine.
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4 ]

Tycho's co-ordinates for the nova were: long: 0° Aries 26' 24";
dec. +61° 46' 45". It is still marked in Norton's Star Atlas as SN1572 but is
now an extremely faint deep-sky object.
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For a general discussion of cosmological systems from the Babylonians to Isaac Newton and biographies of all the major figures in the history of European astronomy see Arthur Koestler's The Sleepwalkers cited above, but be warned - Koestler was implacably hostile to astrology. For details of the technical intricacies of the various systems see Copernicus: The Founder of Modern Astronomy by Angus Armitage, Associated University Press (1990).
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7 ]

Koestler, op.cit., p.315. In view of the manner of his death it is curious to note that Tycho's nativity has no planets in water signs. This may also help explain his ambivalent relationship with Kepler who had no planets in fire. (Kepler's birth data corresponds to 13:53 GMT, 6th January 1572 New Style, lat: 47°N36'; long: 7°E39'.)
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David Plant is a respected scholar of the history and traditional practice of astrology. He is also an expert on the English Civil War period and the life and work of the 17th century astrologer William Lilly. He runs two very reputable websites: the
English Merlin site, which is devoted to all aspects of the life and times of
William Lilly and his contemporaries; and the British Civil Wars and Commonwealth site, which explores the turmoil of the Civil Wars and Interregnum, and the constitutional experiments of the Commonwealth and Protectorate period of the 1650s.
Both sites are leading points of reference for their fields and a visit is strongly recommended.

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